1. Field of the Invention
The present invention relates to toners utilized for electrophotographic processes, electrostatic recording processes, electrostatic printing processes or the like; efficient production methods of the toners; and developers, toner-containing containers, process cartridges, image forming apparatuses and image forming methods that utilize the toners respectively.
2. Description of the Related Art
Electrophotographic processes involve generally a latent electrostatic image forming step in which latent electrostatic images are formed on a photoconductor containing-photoconductive substances by various means, a developing step in which toner images are formed by use of toners, a transfer step in which the toner images are transferred on recording media such as paper, a fixing step in which toner images transferred on the recording media are fixed on the recording media by action of heat, pressure, hot press, solvent vapors or the like, a cleaning step in which toners remaining on the photoconductor surface are removed, and the like.
The toners used in the electrophotographic processes are demanded to be produced by more energy-saving, environment-friendly processes. Conventionally, the toners have been produced by melting, mixing and pulverizing processes; in recent years, polymerization processes in liquid solvents are mainly employed, such as emulsion aggregation processes, emulsion polymerization processes and dispersion polymerization processes. Among the polymerization toners produced by these polymerization processes, functional toners referred to as capsule toners or core shell toners are provided that have a certain configuration to provide efficiently desirable functions from the viewpoint on recent environmental issues.
In the toner producing methods through the melting, mixing and pulverizing processes, it is important that the respective constitutional materials are uniformly dispersed and pulverized for making uniform the shape of resulting toners. Essentially, the shape of pulverized toners is nonuniform and the surfaces are randomly fractured, therefore, the shape and the configuration are remarkably difficult to control. Furthermore, when a great deal of colorants, release agents and charge control agents are added, these additives tend to expose at surfaces due to cleavage at their crystal faces, which possibly induces problems of quality degradation due to polarization of coloring, releasing and charging properties in respective particles.
On the other hand, the toner producing methods through the polymerization processes may provide toners with higher qualities than those of the pulverizing processes described above; however, there exist such problems that the droplets are difficult to control into optional sizes in dispersion solvents, margin of employable materials is relatively narrow, and coloring, releasing and charging properties are liable to deviate due to polarization of the components in the toners.
In view of these problems, Japanese Patent Application Laid-Open (JP-A) No. 2003-21933 discloses a method for producing a toner uniformly containing sufficient amounts of colorants, charge control agents and release agents, in which at least one of colorants, charge control agents and waxes is dispersed in water by use of polymerization initiators, to thereby prepare an aqueous dispersion containing micelles of these ingredients before emulsion polymerization or soap-free emulsion polymerization by use of polymerization initiators having a surface activity and a structure with a hydrophilic site, a hydrophobic site and also a polymerization initiation site therebetween.
However, uniform dispersion and deposition of colorants, charge control agents and release agents cannot be attained sufficiently even the toner production method described in JP-A No. 2003-21933 is employed, thus the developing properties including the lifetime is not sufficiently satisfactory.
Accordingly, such technologies have not been provided yet that can form coating layers of optional materials on toner base particles produced by conventional methods, and can provide the toner base particles with more uniform charging capacities and surface properties, and also can sufficiently solve problems induced by polarization of the colorants, release agents, charge control agents and the like.